Recently Destin from Smater Every Day showed us how a tattoo machine works in mesmerising close-up slow motion - and pretty much broke the internet with all its views.
In the latest episode Destin explores what it takes to get rid of a tattoo - which, as you can see in the episode above, involves some incredibly complex science, like thermodynamics, optics and chemistry.
But in the end it all comes down to this one mindblowingly fascinating fact: doctors need to find a way to get you to poop your tattoo out.
To understand what goes on, you first need to understand a little bit about the ink that tattoo artists use, which many people would be surprised to know is often made up of compounds that use heavy metals such as lead and chromium.
As soon as you get a tattoo, your white blood cells are trying to break down these ink particles under your skin - the reason tattoos are permanent is because the ink particles are too big for the white blood cells to get rid of.
But for the entire life of your tattoo, these cells will be trying to break down the ink and drag it over to the lymph nodes, which will direct it to the liver to be processed and eventually excreted. It's pretty crazy to think about, but this is why tattoos gradually fade over time - your white blood cells are slowly eating away at the ink particles.
To get rid of them altogether, as Destin explains, it takes a super-fast laser that pulses every pico second (that's 0.000000000001 of a second), and is finely tuned to the exact frequency that will cause the ink to rapidly heat up.
Once this laser has heated one side of the ink quickly enough to rip it apart, the white blood cells can do their job and get the ink to the liver and then, finally, into your poop.
Watch the episode above to see fascinating close-up footage of a plastic surgeon erase a tattoo right in front of your eyes, and also witness Destin mix his own blood with ink under the microscope. It will without a doubt be the best thing you see all day.
Source: Smarter Every Day